Updated code examples to working code for 3.4

[kenirwin]

I tried using the existing documentation to set up CakePHP-upload for the first time and ran into a few issues. This pull request reflects the changes I had to make to get it to work.

• As of CakePHP 3.4, the initialize() function uses setTable(), setDisplayField(), and setPrimaryKey() instead of the method names not including 'set';
• It looks like the Form helper used Model names in some earlier version of CakePHP, but those now get left out. I changed to using $user instead of User in lines 47 & 97; I removed the 'User.' from the field names in the input.

[davidyell]

These changes would make the minimum required Cake version 3.4, which won't be to everyone's taste.

Better to keep the older deprecated methods, to broaden compatibility.

[Spriz]

Really 🤔 I mean if not even FoC pushes towards the latest version, then who would?

At least when it's just docs :)

[josegonzalez]

Good catch.

[kenirwin]

Ok -- I've added the old code in comments after each affected code block. Will this work?

[josegonzalez]

Mind adding a note here saying these are for 3.4+, and having the older ones commented out for those who have yet to upgrade cake core?

[kenirwin]

Sure -- I will give it a go.

[Spriz]

I think the $this->Form->create('User', ['type' => 'file']);-part is a leftover from cake 2.x - eh?

[kenirwin]

That could well be. Since I started using cake 2 weeks ago, I will defer to others' experience with that. With that in mind, I've removed the older code.

One other thing I wonder about is this:
$this->setDisplayField('name'); // $this->displayField('name');

There's no name field in the database; it calls for a username. Should that be
$this->setDisplayField('username'); // $this->displayField('username');

It didn't seem to make a difference in behavior for me, but I wonder if it's more correct.

[josegonzalez]

Yeah that should be username, can you change that too?

[kenirwin]

Ok - I've fixed the display name.